Tamper Evident Lid and Method of Making Same

ABSTRACT

A tamper resistant, push-on closure member for a container. The closure has a top cylindrical band portion, a bottom cylindrical band portion and a top cover. The top band has a plurality of continuous annular ridges extending inwardly along the circumference of its inner surface for contacting the side surface of the container. The bottom band has plurality of rigid teeth extending from a lower peripheral margin of the bottom band in an upward and inward direction for locking engagement against the lip of the container. The plurality of teeth are connected to a lower peripheral margin of the top band by a plurality of projections for providing a visual tamper evident indication. A plurality of tooth channels positioned between the lower margin of the top band and the upper margin of the bottom band for facilitating the flow of plastic resin during the production of the plurality of teeth.

FIELD OF THE INVENTION

The invention relates generally to lids for containers and particularly to tamper-resistant, tamper-evident lids for containers for products that present significant concerns for the consumer about unauthorized tampering with the product (e.g. food products and other consumables).

BACKGROUND OF THE INVENTION

In the ice cream packaging industry, a variety of closure arrangements are used to hold a paperboard, plastic or composite lid in place on the paperboard container or tub holding the ice cream. Examples include U.S. Pat. No. 6,772,901 (Witt), U.S. Pat. No. 7,703,626 (Witt), and U.S. Pat. No. 6,053,353 (Helms).

Previous solutions involve complex processes for incorporating a paperboard top within a closure. For example, U.S. Pat. No. 6,772,901 (to the present inventor Witt) describes that a paper top is peripherally sealed to a downwardly-recessed annular ridge of a plastic rim by induction heating, ultrasonic welding or spin welding. U.S. Pat. No. 6,772,901 (to the present inventor Witt) describes that in the alternative, the paper top may be sealed to the annular ridge by applying a coating of adhesive to either side of the face surfaces prior to insertion of the paper lid. U.S. Pat. No. 7,703,626 (to the present inventor Witt) describes the pre-assembly heating of the closure components with directed hot air to partially melt the thermoplastic surfaces and allow the parts to be immediately assembled sealingly, and describes a paperboard composite closure in which the plastic rim is of a two-piece snap-fit construction where the paperboard is compressed between first and second annular flanges of the two-piece plastic rim.

It is of great and increasing importance that the consumer, at the point of purchase of a product, be confident that the package that he or she intends to purchase has not been compromised. If there is a problem with the packaging which cannot be spotted until the consumer opens it for use, he or she may well never purchase that product again and consumer confidence is reduced generally.

SUMMARY OF THE INVENTION

There is provided a lid that can be used to resist and make readily detectable tampering of the products at the point of sale. Particular examples include dairy products, cosmetics, granular or powdered food products such as tubs for bread crumbs, hardware product tubs for screws, nuts and bolts, and so on.

According to one aspect of the invention, a tamper-resistant tamper-evident container closure is provided for ice cream, dairy and other food products that are commercially practical and provides the level of tamper evidence needed for food safety.

According to the present invention, there is provided a tamper resistant push-on closure member for a container having an opening with a peripheral lip formation, comprising: a top cylindrical band portion having an upper peripheral margin and a lower peripheral margin, the top cylindrical band portion having a plurality of continuous annular ridges extending inwardly along the circumference of its inner surface for contacting the side surface of the container; a bottom cylindrical band portion having an upper peripheral margin and a lower peripheral margin; the bottom cylindrical band portion being circumscribed by a rupturable line of weakness vertically below the lower peripheral margin of the top cylindrical portion; a plurality of rigid teeth extending from the lower peripheral margin of the bottom cylindrical band portion in an upward and inward direction for locking engagement against the lip of the container when the closure member is in place; and a top cover portion formed from generally flexible sheet material, peripherally sealed to an annular ledge on the upper peripheral margin of the top cylindrical band portion.

As well, there is provided a closure member where the top of the plurality of rigid teeth are connected to the lower peripheral margin of the top cylindrical band portion by a plurality of projections for providing a visual tamper evident indication and for increasing the force of engagement of the plurality of teeth against the lip of the container.

Also, there is provided a closure member having a plurality of tooth channels positioned between the lower peripheral margin of the top cylindrical band portion and the upper peripheral margin of the bottom cylindrical band portion for facilitating the flow of plastic resin during the production of the plurality of rigid teeth.

Additionally, there is provided a closure member where the bottom of the plurality of teeth are connected to the lower peripheral margin of the bottom cylindrical band portion by a plurality of inner projections for increasing the rigidity of the plurality of teeth and for increasing the force of engagement of the plurality of teeth against the lip of the container.

As well, there is provided a composite tamper resistant push-on closure member for a container having an opening with a peripheral outwardly extending lip formation, the closure comprising: a top cover; a cylindrical closure, the cylindrical closure comprising: a top cylindrical band portion having an upper peripheral margin extending from the top cover portion, and a lower peripheral margin;a bottom cylindrical band portion having an upper peripheral margin and a lower peripheral margin; a rupturable line of weakness between the lower peripheral margin of the top cylindrical band portion and the upper peripheral margin of the bottom cylindrical band portion; and a plurality of rigid teeth extending from the lower peripheral margin of the bottom cylindrical band portion in an upward and inward direction for locking engagement against the lip of the container when the closure member is in place; the top cylindrical band portion having an annular recess along the inner circumference of the upper peripheral margin for receiving and securing a peripheral margin of the top cover.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference will be made, by way of example, to the accompany drawings which show example embodiments of the present application, and in which:

FIG. 1 is a plan view of the top of the example closure of FIG. 1; and

FIG. 2 is a cross-sectional view of the example closure of FIG. 1, across line A-A of FIG. 1;

FIG. 3 is a cross-sectional portion view of the example closure of FIG. 1;

FIG. 4A is a perspective view of the example closure of FIG. 1 with a container;

FIG. 4B is a perspective view of the example closure of FIG. 1 attached to a container;

FIG. 5 is a outer side view of the example closure of FIG. 1;

FIG. 6A is a cross-sectional view of the example closure of FIG. 1 with a container;

FIG. 6B is a cross-sectional portion view of the example closure of FIG. 1 with a container;

FIG. 7A is a cross-sectional view of the example closure of FIG. 1 attached to a container; and

FIG. 7B is a cross-sectional portion view of the example closure of FIG. 1 attached to a container.

DESCRIPTION OF EXAMPLE EMBODIMENTS

FIG. 1 shows an example closure 10 in accordance with the present disclosure. The closure 10 is a snap-on closure such as a lid, and may be suitable for use to close an opening of a food container such as a plastic or paperboard container (e.g., an ice cream container). The closure 10 may be manufactured using a one-piece molding process, as described further below.

As shown in FIG. 2, the closure 10 may include a top cover portion 20, a top cylindrical band portion 30 with upper and lower margins 30 a and 30 b, respectively, and a bottom cylindrical band portion 40 with upper and lower peripheral margins 40 a and 40 b, respectively. The top cylindrical band portion 30 and the bottom cylindrical band portion 40 are integrally formed and connected, and these portions 30, 40 as a single unit may be referred to in the application as the cylindrical closure portion 15. The top cylindrical band portion 30 and the bottom cylindrical band portion 40 are connected by a line of weakness 50 as described below.

At the top peripheral margin 30 a the top cylindrical band portion 30 has a circumferential projection 34 that is recessed from the outer side of the top cylindrical band portion 30 and extends upwardly and inwardly. The bottom of the projection 34 provides an annular ledge 18.

As shown in FIG. 1, the top cover panel 20 may consist of a paper disk or the like that may be printed on its upper side for product identification, marketing information, graphics etc. Particularly for use with ice-cream and food products, the cover panel 20 will have a polymer layer attached to the underside for keeping moisture from the product from entering through the paper. In the embodiment illustrated in FIGS. 3, 6A, 6B, 7A and 7B, the top cover panel 20 is continuous with the annular ledge 18.

As shown in FIG. 2, the bottom cylindrical band portion 40 has a plurality of circumferentially spaced tamper evident tooth system 70 (may also be referred to herein as tamper resistant teeth). Extending upwardly and inwardly from the lower peripheral margin 40 b of the bottom cylindrical band 40 at the plurality of tamper evident tooth system 70 are a plurality of circumferentially spaced teeth 60. The plurality of teeth 60 lock under the rim of the container when the closure 10 is first pushed downwardly to seal the container. The plurality of teeth 60 act as a tamper resistant mechanism on the closure 10.

As shown in FIG. 2, the plurality of teeth 60 may include notches 64, 66 located at the right and left sides of a top edge 62 of the teeth 60. The notches 64, 66 may further facilitate the locking engagement of the plurality of teeth 60 of the rim of the container.

As shown in FIGS. 3 and 4B, for each tamper evident tooth system 70, between the plurality of teeth 60 and the lower peripheral edge 30 b of the top cylindrical band portion 30 is an open space. Each tamper evident tooth system 70 further has a plurality of projections 72 that connect the plurality of teeth 60 to the bottom peripheral area 30 b of the top cylindrical band portion 30. The plurality of projections 72 may be seen when viewing the outer side of the closure 10, providing an effective means for determining if the closure 10 has been tampered with. Additionally, the plurality of projections 72 may function to increase the force of engagement of the plurality of teeth 60 against the lip of the container.

As shown in FIGS. 2 and 3, along the inner side of each tamper evident tooth system 70 there are two or more projections 76 that are connected to the bottom of the plurality of teeth 60 to the lower peripheral margin 40 b of the bottom cylindrical band portion 40. The projections 76 may provide additional rigidity to the plurality of teeth 60 and also may assist in increasing the force of engagement of the plurality of teeth 60 against the lip of the container.

As shown in FIG. 2, the upper peripheral margin 40 a of the bottom cylindrical band portion 40 is thinned and weakened. In the embodiment shown in FIGS. 2, 3, 4B, and 5, the line of weakness 50 includes one or more of a circumferential notch 52, the plurality of projections 72, and open spaces that are viewable from the outer side of the bottom cylindrical band portion 40. Legitimate opening of the container by a consumer starts by separating the top cylindrical band portion 30 from the bottom cylindrical band portion 40 by tearing away the bottom cylindrical band portion 40 along the line of weakness 50.

For convenience in legitimately opening the container, the bottom cylindrical band portion 40 is provided with a gripping means. In an embodiment shown in FIGS. 1, 4A and 4B, the bottom cylindrical band 40 is formed with an accessible edge portion 45 disposed at a location along the outwardly facing surface. The accessible edge portion 45 may include projections or ridges on its outer surface that assist a user's ability to grip and hold the portion 45. By exerting moderate force on the accessible edge portion 45, the bottom cylindrical band portion 40 below the line of weakness 50 can be removed with the plurality of teeth 60 as a tear-away strip. That is, the line of weakness 50 is ruptured and the bottom cylindrical band portion 40 having the plurality of teeth 60 is easily removed from the closure 10 and from the container (not shown).

In some embodiments as shown in FIGS. 3, 6A, 6B, 7A, and 7B, the closure 10 has a multi-snap closing. The inner surface 32 of the top cylindrical band portion 30 may have a plurality of continuous annular ridges 38 extending inwardly along the circumference of the inner surface 32. As shown in FIGS. 7A and 7B, the plurality of continuous annular ridges 38 provide multiple contact points against a paperboard or cardboard rim 102 of a container 100. As paperboard and cardboard rims are flexibly irregular, the plurality of continuous annular ridges 38 provide multiple places to contact the paperboard rim 102, thereby improving the seal of the closure 10 on the container 100. As well, when the bottom cylindrical band portion 40 has been removed, the plurality of continuous annular ridges 38 provide an improved mechanism for resealing the container 100.

The top cylindrical band 30 and the bottom cylindrical band 40 of the closure 10 may be manufactured by a one-piece molding process, such as injection-molding, using a single mold. This one-step process may help to simplify manufacturing and/or reduce manufacturing costs. The closure 10 may be molded using any suitable polymer, for example any suitable food-grade plastic when used as a closure for a food container (e.g., used as a lid on a yogurt or ice cream container).

As well, in another embodiment, the cover panel 20 may be made of the same plastic material as the top cylindrical band portion 30 and the bottom cylindrical band portion 40.

Accordingly, in this embodiment, the cover panel 20, the top cylindrical portion 30 and the bottom cylindrical portion 40 may be manufactured by a one-piece molding process, such as injection-molding, using a single mold.

The closure 10 of the present application has specific elements that facilitate the molding process. As shown in FIGS. 1 and 2, the closure 10 has one or more openings or gates 80 located on the upper peripheral portion 30 a of the top cylindrical band portion 30. The gates 80 act as an opening for the plastic resin to enter a mold and fill the mold cavity.

As shown in FIGS. 3, 4B and 5, the upper peripheral portion 40 a of the bottom cylindrical band portion 40 has multiple tooth channels that allow the plastic to flow into the tamper evident tooth system 70. The tamper evident tooth system 70 includes the plurality of teeth 60 that is formed on the bottom cylindrical band 40 and the plurality of projections 72. The plurality of projections 72 define and/or delineate the tooth channels in the corresponding mold. The tooth channels improve the process of filling the mold cavity and also increases the speed by which the tamper evident tooth system 70 that includes the plurality of teeth 60 and the projections 72 are formed. As well, the tooth channels reduce the amount of defects in the tamper evident tooth system 70. Also, the tooth channels further facilitate the creation of larger and thicker tamper resistant bands than conventional solutions, thereby increasing the rigidity of the plurality of teeth 60.

As shown in FIG. 2, the tamper evident tooth system 70 has edges 64, 66 that slope inwardly. During the injection molding process, the cover panel 20 is inserted into the mold. The mold is filled with resin by injection. The resin covers the edge of the paper cover panel 20, creating the lid. The mold then collapses at the edges of the tamper evident tooth system 70 to facilitate and the ejection of the part from the mold.

FIG. 4A illustrates the closure 10 with a container 100 and FIG. 4B illustrates the closure 10 attached to the container 100. In an embodiment as shown in FIGS. 4A, 4B, 6A and 6B, the disc is inserted into the mold and then plastic resin is molded around the top and bottom to hold it in place. In other embodiments, a coating of suitable adhesive may be applied to either of the outer edge of the facing surfaces prior to insertion of cover panel 20 onto the annular ledge 18 located on the bottom of the projection 34. Alternatively, heating, ultrasonic welding, or spin welding may be used. In another embodiment, the cover panel 20 is secured to the top cylindrical band 30, by the interference fit in recess 19. The cover panel 20 is secured to the cylindrical closure portion 15 prior to attaching the closure 10 to the container 100 (FIG. 4B). The closure 10 is attached to the container 100 by applying a downward force to the top to the closure 10 onto the top of the container 100. As previously discussed, the plurality of teeth 60 of the closure 10 lock under the rim of the container when the closure 10 is pushed downwardly to seal the container.

FIGS. 6A and 6B illustrate an embodiment for incorporating the cover panel 20 into the cylindrical closure portion 15. As shown in FIGS. 6A and 6B, during assembly the cover portion 20 may be positioned above the container 100. For example, the cover portion 20 may be placed to sit and rest on the circumferential paperboard rim 102 of the container 100. As well, the cylindrical closure portion 15 is positioned above the cover portion 20. At this stage of assembly, the container 100 would contain a material or food product to be sealed.

To seal the container 100 with the cylindrical closure portion 15 and the cover portion 20, downward force is applied to attach the cylindrical closure portion 15 onto the cover portion 20 and the top of the container 100. As shown in FIGS. 7A and 7B, the cylindrical closure portion 15 snaps onto the paperboard rim 102 and in this process, the cover portion 20 is secured to the cylindrical closure portion 15. For example, the cover portion 20 is pushed into position in the upper cyclindrical band portion 30 and is secured within an annular recess 19 located along the inner circumference of the upper peripheral margin 30 a of the top cylindrical band portion 30. In some embodiments, the cover portion 20 may also have an adhesive applied to its top circumference to further secure the cover portion 20 to annular ledge 18 of the top cylindrical band portion 30.

As shown in FIGS. 7A and 7B, the plurality of teeth 60 lock under the rim of the container when the closure 10 pushed downwardly to seal the container. As well, as shown in FIGS. 7A and 7B once the closure 10 is attached to the container 10, the plurality of continuous annular ridges 38 provide multiple contact points against the paperboard rim 102 of a container 100, providing an improved interference fit. This improves the seal of the closure 10 on the container 100. As well, when the bottom cylindrical band portion 40 has been removed, the plurality of continuous annular ridges 38 provide an improved mechanism for resealing the container 100.

In the embodiments shown in the figures, the lid is circular. In other embodiments, it is rectangular, oval, square, or other shapes.

Although a particular embodiment of the invention has been illustrated and described herein, one of ordinary skill in the art will appreciate that changes or additions may be made to the design of the closure without departing from the scope of the invention, which is defined in the claims attached hereto. For example, a solid resilient band might be used on the tear-away strip portion of the closure instead of individual tamper-evident teeth. In lieu of paperboard, different flexible sheet materials might be used, according to the final intended application. The inside wall of the top cylindrical band could be formed with threads to adapt the closure for use on a threaded container. 

1. A one piece tamper resistant push-on closure member for a container having an opening with a peripheral outwardly extending lip formation, the closure comprising: a top cover portion; a top cylindrical band portion having an upper peripheral margin extending from the top cover portion, and a lower peripheral margin; a bottom cylindrical band portion having an upper peripheral margin and a lower peripheral margin; a rupturable line of weakness between the lower peripheral margin of the top cylindrical band portion and the upper peripheral margin of the bottom cylindrical band portion; and a plurality of rigid teeth extending from the lower peripheral margin of the bottom cylindrical band portion in an upward and inward direction for locking engagement against the lip of the container when the closure member is secured on the container; the top cylindrical band portion having a plurality of continuous annular ridges extending inwardly along the circumference of an inner surface each of said ridges for contacting a side surface of the container in an interference fit.
 2. The closure member according to claim 1, wherein the plurality of teeth are connected to the lower peripheral margin of the top cylindrical band portion by a plurality of projections for providing a visual tamper evident indication and for increasing the force of engagement of the plurality of teeth against the lip of the container.
 3. The closure member according to claim 1, further comprising: a plurality of tooth channels positioned between the lower peripheral margin of the top cylindrical band portion and the upper peripheral margin of the bottom cylindrical band portion for facilitating the flow of plastic resin during the production of the plurality of rigid teeth.
 4. The closure member according to claims 1, wherein a bottom of the plurality of teeth are connected to the lower peripheral margin of the bottom cylindrical band portion by a plurality of inwardly extending projections for increasing the rigidity of the plurality of teeth and for increasing the force of engagement of the plurality of teeth against the lip of the container.
 5. (canceled)
 6. (canceled)
 7. (canceled)
 8. A one piece tamper resistant push-on closure member for a container having an opening with a peripheral outwardly extending lip formation, the closure comprising: a top cover portion; a top cylindrical band portion having an upper peripheral margin extending from the top cover portion, and a lower peripheral margin; a bottom cylindrical band portion having an upper peripheral margin and a lower peripheral margin; a rupturable line of weakness between the lower peripheral margin of the top cylindrical band portion and the upper peripheral margin of the bottom cylindrical band portion; a plurality of rigid teeth extending from the lower peripheral margin of the bottom cylindrical band portion in an upward and inward direction for locking engagement against the lip of the container when the closure member is secured on the container; and a plurality of tooth channels positioned between the lower peripheral margin of the top cylindrical band portion and the plurality of rigid teeth of the bottom cylindrical band portion for facilitating the flow of plastic resin during the production of the plurality of rigid teeth.
 9. The closure member according to claim 8, wherein the plurality of teeth are connected to the lower peripheral margin of the top cylindrical band portion by a plurality of projections for providing a visual tamper evident indication and for increasing the force of engagement of the plurality of teeth against the lip of the container.
 10. The closure member according to claim 8, wherein the top cylindrical band portion has a plurality of continuous annular ridges extending inwardly along the circumference of an inner surface each of said ridges for contacting a side surface of the container in an interference fit.
 11. The closure member according to claims 8, wherein a bottom of the plurality of teeth are connected to the lower peripheral margin of the bottom cylindrical band portion by a plurality of inwardly extending projections for increasing the rigidity of the plurality of teeth and for increasing the force of engagement of the plurality of teeth against the lip of the container.
 12. (canceled)
 13. (canceled)
 14. (canceled)
 15. A one piece tamper resistant push-on closure member for a container having an opening with a peripheral outwardly extending lip formation, the closure comprising: a top cover portion; a top cylindrical band portion having an upper peripheral margin extending from the top cover portion, and a lower peripheral margin; a bottom cylindrical band portion having an upper peripheral margin and a lower peripheral margin; a rupturable line of weakness between the lower peripheral margin of the top cylindrical band portion and the upper peripheral margin of the bottom cylindrical band portion; and a plurality of rigid teeth extending from the lower peripheral margin of the bottom cylindrical band portion in an upward and inward direction for locking engagement against the lip of the container when the closure member secured on the container; wherein lateral sides of the plurality of teeth are connected to the bottom cylindrical band portion by side walls for increasing the rigidity of the plurality of teeth and for increasing the force of engagement of the plurality of teeth against the lip of the container.
 16. The closure member according to claim 15, wherein the bottom of the plurality of teeth are connected to the lower peripheral margin of the bottom cylindrical band portion by a plurality of inwardly extending projections for increasing the rigidity of the plurality of teeth and for increasing the force of engagement of the plurality of teeth against the lip of the container.
 17. The closure member according to claim 15, wherein the plurality of teeth are connected to the lower peripheral margin of the top cylindrical band portion by a plurality of projections for providing a visual tamper evident indication and for increasing the force of engagement of the plurality of teeth against the lip of the container.
 18. The closure member according to claim 15, further comprising: a plurality of tooth channels positioned between the lower peripheral margin of the top cylindrical band portion and the upper peripheral margin of the bottom cylindrical band portion for facilitating the flow of plastic resin during the production of the plurality of rigid teeth.
 19. (canceled)
 20. (canceled)
 21. (canceled)
 22. The closure member according to claim 15, wherein the top cylindrical band portion has a plurality of continuous annular ridges extending inwardly along the circumference of an inner surface each of said ridges for contacting a side surface of the container in an interference fit.
 23. A composite tamper resistant push-on closure member for a container having an opening with a peripheral outwardly extending lip formation, the closure comprising: a top cover; a cylindrical closure, the cylindrical closure comprising: a top cylindrical band portion having an upper peripheral margin extending from the top cover portion, and a lower peripheral margin; a bottom cylindrical band portion having an upper peripheral margin and a lower peripheral margin; a rupturable line of weakness between the lower peripheral margin of the top cylindrical band portion and the upper peripheral margin of the bottom cylindrical band portion; and a plurality of rigid teeth extending from the lower peripheral margin of the bottom cylindrical band portion in an upward and inward direction for locking engagement against the lip of the container when the closure member is secured on the container; the top cylindrical band portion having an annular recess along an inner circumference of the upper peripheral margin for receiving and securing a peripheral margin of the top cover; wherein a bottom of the plurality of teeth are connected to the lower peripheral margin of the bottom cylindrical band portion by a plurality of inwardly extending projections for increasing the rigidity of the plurality of teeth and for increasing the force of engagement of the plurality of teeth against the lip of the container.
 24. The closure member according to claim 23, further comprising: a plurality of tooth channels positioned between the lower peripheral margin of the top cylindrical band portion and the upper peripheral margin of the bottom cylindrical band portion for facilitating the flow of plastic resin during the production of the plurality of rigid teeth.
 25. The closure member according to claim 23, wherein the closure is formed of plastic material in a single injection molding step.
 26. The closure member according to claim 23, wherein the rupturable line of weakness is an apex of a circumferential groove along an outer wall of the bottom cylindrical band portion.
 27. The closure member according to claim 23, wherein an accessible edge portion is formed in the bottom cylindrical band portion to permit ready gripping and tearing a part of the bottom band below the line of weakness.
 28. The closure member according to claim 23, wherein the top cylindrical band portion has a plurality of continuous annular ridges extending inwardly along the circumference of an inner surface each of said ridges for contacting a side surface of the container in an interference fit.
 29. A method of molding a composite tamper resistant push-on closure member of claim 23, the method comprising: placing a top cover in a mold; filling the mold with a resin to form a cylindrical closure comprising: a top cylindrical band portion having an upper peripheral margin extending from the top cover portion, and a lower peripheral margin; a bottom cylindrical band portion having an upper peripheral margin and a lower peripheral margin; a rupturable line of weakness between the lower peripheral margin of the top cylindrical band portion and the upper peripheral margin of the bottom cylindrical band portion; and a plurality of rigid teeth extending from the lower peripheral margin of the bottom cylindrical band portion in an upward and inward direction for locking engagement against the lip of the container when the closure member is secured on the container; wherein the resin secures to a peripheral margin of the top cover.
 30. The method of claim 29, further comprising a plurality of tooth channels positioned between the lower peripheral margin of the top cylindrical band portion and the plurality of rigid teeth of the bottom cylindrical band portion for facilitating the flow of resin during the production of the plurality of rigid teeth.
 31. The method of claim 29, further comprising applying an adhesive between an annular wall of an annular recess near the upper peripheral margin of the top cylindrical band portion and the peripheral margin of the top cover.
 32. The method of claim 31, further comprising one or more of heating the annular wall and the peripheral margin of the top cover, ultrasonic welding the annular wall to the peripheral margin of the top cover, and spin welding the annular wall to the peripheral margin of the top cover.
 33. (canceled)
 34. (canceled) 